Ordovician between Pilzno and Busko in the Carpathian Foreland (Southern Poland)

Abstract

The Ordovician carbonates encountered in tlie Pilzno 40 borehole at depth of 3593-3733 m have yielded index conodonts and ostracods which enabled to determine the age of the rocks as Llandeilo and Caradoc. Comparison with columns of other 6 boreholes in the area has shown a significant facies differentiation: Lower Ordovician sandstones of the western part pass east-wards into shales. Middle Ordovician shales in the northern sector are replaced by carbonates to the south. Ordovician is preserved in narrow synclines formed during the Caledonian and Early Variscan stages. Earlier, it covered greater areas and was removed by post-Variscan erosion. Ordovician transgression has proceeded from north to south.